Peptic Ulcer and Helicobacter pylori infection:

In 1982, Barry Marshall and Robin Warren, reported that

H.pylori is associated with chronic gastritis and gastric

ulcers, conditions that were not previously believed to have

a microbial cause.

However, over 80 percent of individuals infected with the

bacterium are asymptomatic patients.

More than 50% of the world's population harbor H. pylori

in their upper gastrointestinal tract.

Microscopy: H. pylori is a curved rod, helix-shaped, Gram-negative bacterium measuring about (3 L*0.5 D ) micrometers .

All Species are Pleomorphic; Bacillary, spiral, and Coccoidal shape. All are motile by four to six lophotrichous flagella.

Helicobacter pylori species arenon-Spore formers, and most strainshave a glycocalyx.

Cultural characteristics: All Helicobacter pylori species are Fastidious Microaerophilic in nature.

The cultivation Enrichment -media:- Brain heart infusion broth supplemented by fetal calf serum (10%) or/and Bovine serum albumin. - Brucella broth supplemented by fetal calf serum (10%).

The selective Enriched media:- Columbia chocolate agar supplemented by 5-10% hemolyzed sheep blood, and specific antibiotics combination ( 5mg/L trimethoprim, 6mg/L vancomycin, and 6mg/L amphotericin B).

N

Both Enrichment and Enriched media should be inoculated by the clinical specimens and incubated at 37ᵒC with a microaerophilic atmosphere ( 10% CO2, 5% O2, and 85% N2) for up to8 days ( humidity should be > 95%).

Colony morphology:-H. pylori species produce a specific colonies with the following characteristics : small (0.5-2mm), round, convex, translucent, withenteric margin and non-hemolytic activity.

Biochemical identification: All Helicobacter pylori species show immediate positive oxidase , catalase, and urease (++++) reactions. All species are also demonstrating alkaline phosphatase, gamma – glutamyl aminopeptidase , and ornithine decarboxylase activities.

Biotyping of Helicobacter pylori:

Almost all strains of Helicobacter pylori are sensitive to Cephalothinand resistant to Nalidixic acid.

Helicobacter pylori Virulence factors: - Outer membrane proteins: 1-The adhesins protein : adhesion to host cell. 2- Porins proteins, iron transporters, and Flagella proteins.- The Lipopolysaccharide (LPS)- O antigen: mimic Lewis blood group antigen found on the gastric epithelium - The Exotoxins: The Vacuolating (Vac A) toxins: : gastric mucosal injury.- The Secretory Enzymes: 1- The Urease: Neutralize gastric acid, and mucosal injury. 2- The mucinase, lipase, protease: mucosal injury. - The Flagella : motility.- The effector cytotoxin : The cytotoxin associated gene A (Cag A): cause uncontrolled host cell growth and apoptosis inhibition.

Helicobacter pylori Virulence factors: N

Pathogenesis and clinical picture: Transmission :1- Person to Person (Oral-Oral or Fecal-Oral). 2- Waterborne mainly within People living in crowded condition, inadequate sanitation practices, and poor hygiene. 3-Iatrogenic transmission: mediated by contaminated Endoscopy.

1-Primary infection: -H. pylori enters the stomach. - To avoid being carried into the lumen, H. pylori senses the pH- gradient and swims away from the acidic microenvironment. - The microbe invades the mucus layer .

N

- Ammonia will neutralize gastric acid and damage the epithelial cells of gastric mucosa. - The microbial toxins will also destroy epithelial mucosa. - Colonization of gastric mucosa stimulates chemotaxis of

phagocytes, lymphocytes and cellular immunity. - Antrum Gastritis ( acute infection).- Corpus Gastritis ( acute infection).- Both types of gastritis could lead to gastric ulceration. (gastric acid concentration reduced) - Duodenal ulceration : (mainly chronic infection): (gastric acid concentration increased). - Duodenal atrophy: ( chronic infection): (gastric acid concentration decreased). - The risk of stomach cancer increased by chronic infection.

a

2- Secondary infection: Latency.

Pathogenesis and clinical picture: a

NThe secondary and chronic infections caused by Toxigenic Helicobacter pylori strains (Cag A +++) could be complicated by:

1- Adenocarcinoma of the stomach.

2- MALToma of the stomach:

It is a rare type of Non-Hodgkin’s lymphoma of the stomach (B-cell Lymphoma).

Chronic ulceration of stomach and duodenum could be converted into Bleeding ulceration.

Clinical picture of H. pylori: n

n

n

Diagnosis: 1- Clinical diagnosis: A- Endoscopy: gastritis, ulcers, bleeding ulcer, atrophy. B- CLO test: Rapid diagnostic test. C- Carbon urea breath test: 13C-UREA swallowed, 13-CO2 exhaled.

2-Laboratory diagnosis: A-Microbiology: tissue biopsy: culture for isolation of H. pylori. : antibiotic sensitivity by Microbroth dilution method.

B-Serology: detection of anti-Helicobacter antibodies or Anti-Cag A antibodies in serum.

C-Histology: biopsy tissue prepared for Giemsa stain and silver stain for H. pylori. H&E stain.

Laboratory diagnosis: Gastric antrum: H&E Stain

Gastric antrum: Giemsa stain.

Clinical and Laboratory diagnosis:Warthin-Starry’s silver stain Immunohistochemistry stain for H.pylori.

The CLO test.